JP6861217B2 - Tribology system and internal combustion engine with it - Google Patents

Description

The present invention relates to a tribology system comprising a first body and a second body, each of which forms a component of an internal combustion engine, in particular a piston, piston ring or cylinder, in general and in particular, the surface of the component being a first material. It has an area and a second material area, each formed as a layer and in contact with each other in at least some areas during operation to form a tribological contact.

The present disclosure relates to both the layer material used to produce the layer and the method by which these layers are applied to the corresponding engine component. It also relates to correspondingly coated engine components.

Additionally, the present disclosure specifically relates to the choice of combination of layer materials coated by a tribology partner in a tribology system.

The term "internal combustion engine" is used herein to include all internal combustion engines that can operate on fossil fuels such as gasoline, diesel or gas fuels (CNG, LNG), in particular reciprocating piston engines.

Increasing the operating temperature in internal combustion engines for the purpose of good fuel utilization and the use of additives such as biofuels imposes surface thermal and chemical stability on gasoline, diesel and gas combustion engines. The demand is high. These high demands can only be met to a limited extent or at great cost by selecting compact materials (also referred to as bulk materials) for engine components.

The term "compact material" or "bulk material" refers to the material of the substrate to be coated to improve surface properties. The material includes all materials that can be coated, such as steel, Al, Inconel, etc., i.e. materials from which components of internal combustion engines are produced and engineering materials. Among the steels, for example 42CrMo4, is a typical material from which a piston is made.

One way to cost-effectively improve the properties of compact materials is, for example, surface treatment with spray coating of powder or wire using nitriding, physical vapor deposition (PVD), or thermal spraying (HVOF or plasma). is there. These processes can only be produced with materials that cannot be produced as compact materials, or with great effort, but even if the modifications affect only the relatively thin areas of the surface of the compact material surface. It can be used to produce materials, which can have a dramatic effect on wear, friction and corrosion.

Typically, the surface of a tribology partner in an internal combustion engine consists of different materials or different compact materials, which are optimized for a given service life to reduce the number of service cycles. That is, the service life is adapted. In such cases, the material or layer thickness is usually adjusted.

In addition to the desire to reduce wear, reducing friction loss is another goal in the development of internal combustion engines. Even under this aspect, the targeted surface modification plays an important role in the tribology system. In addition to the mechanical properties of multiple surfaces and their mutual compatibility, the surface material also has a predetermined controllability of wettability with oils and chemical reactions of additives and surfaces so as not to be chemically unstable. It is supposed to have important functions such as. All of these facts indicate that the tribology system of an internal combustion engine is extremely complex and requires flexibility in the selection and adjustment of multiple surfaces. The thin layer here gives a higher degree of flexibility than the compact material.

Patent Document 1 describes a coating on the inside of a cylinder, that is, a cylinder running surface. The layer is applied by plasma spraying. The mostly iron layer also contains FeO and Fe2O3, the proportion of bound oxygen thereof being 1-4% by weight, and the proportion of Fe2O3 being less than 0.2% by weight. Mixing the oxide ceramic powder in a proportion of 5-50% by weight with respect to the process gas is recommended as a particular advantage to achieve a fairly good coefficient of friction. TiO2, Al2O3-TiO2 and Al2O3-ZrO2 are shown as oxide ceramic powders.

Patent Document 2 claims a cylinder running surface layer for a reciprocating piston engine, and this layer is applied by a plasma spraying method. The layer produced by this method has a bound oxygen content of 0.5-8% by weight and contains embedded FeO and Fe2O3 crystals. In addition, this layer has a porosity of 0.5-10% and is polished to a predetermined roughness. The pores of this layer form a microchamber that acts as a reservoir for the lubricant and promotes uniform dispersion of oil in the tribology system.

Patent Document 3 describes a surface treatment of a piston ring composed of a combination of surface nitriding and PVD coating. From the running surface of the piston ring to the running surface of the cylinder, the CrN layer is coated and preferably deposited by ion plating. All other surfaces undergo a nitriding process. The deposition of PVD layers on the surface of non-nitriding piston rings is primarily intended to prevent cracks in the coating.

Patent Document 4 claims a coated piston ring made of an iron-based material. A wear-resistant layer containing Al5Fe2 and having high hardness is deposited on the surface. The document also claims the chemical composition of this layer consisting of 52-55% by weight Al and 45-48% by weight Fe.

Patent Document 5 describes a tribology system including a piston and a cylinder running surface. The piston also has a recess for a piston ring that makes tribological contact with the cylinder liner. In addition, the piston skirt is designed so that its surface is provided with a groove structure to improve the lubricating film. Piston rings and piston skirts are also coated with a DLC layer, especially in combination with and adapted to various lubricants, to improve sliding properties.

In these examples, the surface is coated to reduce wear and friction loss. Various coating materials can be used to achieve this goal. Different processes are used to apply these materials to the surface of the substrate. Furthermore, the state-of-the-art technology has made it clear that under each condition it is necessary to coat very different substrate materials to achieve favorable surface conditioning of the tribology contact partner.

In some cases, the geometry of the component to be coated also determines the coating process. This is the case, for example, when the cylinder bore needs to be coated. The thermal spraying method is far more suitable than the PVD method for coating the inner part of this component in this way. Such a method is far more effective than PVD coating, even when thick layers greater than 100 μm or greater than 500 μm must be deposited. This has an economic advantage for thin layers in the range up to 10 μm or 30 μm if the substrate can be coated in a batch process.

Testing the layer pairing of a special tribology system for wear and friction loss can, of course, be best performed in a real internal combustion engine. However, such tests are too costly to perform on all possible material combinations. In addition, there is a risk that unknown material combinations can damage the internal combustion engine. This damage can also result in the destruction of the entire test stand

The above shows both the variety of possibilities and how difficult it is to select layers and pair them.

Therefore, the purpose is to provide an improved tribology system specifically for internal combustion engines. Here, each of the two bodies forms a component of an internal combustion engine, and two material areas are formed on their surfaces, and the material areas come into contact with each other in at least a predetermined area during operation to form a tribological contact. To do. Specifically, there is a need to improve the tribology system consisting of piston rings and cylinders or cylinders and pistons. The purpose here is also to provide additional materials or material combinations in which material areas designed as layers can be produced, in particular.

European Patent No. 1022351 (B1) European Patent Application Publication No. 1340834 (A2) International Publication No. 2015/128178 (A1) U.S. Patent Application Publication No. 2014/0260959 (A1) U.S. Pat. No. 7,406,940 (B2)

According to the first aspect, the present disclosure provides a tribology system having a first body and a second body. Each of these is a component of an internal combustion engine, more specifically a piston, piston ring or cylinder. Their surfaces have a first material area and a second material area that come into contact in at least some areas during operation to form a tribological contact. The first material area and / or the second material area is formed as a chromium oxide-based or aluminum aluminum oxide-based layer. Further aspects and features are derived from the dependent claims, the accompanying drawings, and the description of the following embodiments.

Hereinafter, a plurality of embodiments will be described by way of example and with reference to the accompanying drawings.

A schematic cross-sectional view of a plurality of components from an internal combustion engine according to the present invention is shown. This includes the tribology system according to the present invention. The enlarged cross section A of FIG. 1 is shown. This exemplifies the first tribology system according to the present invention. The system is made up of cylinders and piston rings. The enlarged cross section B of FIG. 1 is shown. This exemplifies the second tribology system according to the present invention. The system is made up of cylinders and pistons. Details C of FIG. 1 are shown. This exemplifies a cylinder bottom with a coating. A schematic diagram of SRV test settings for a drying test (example of the left hand) and a lubrication test (example of the right hand) for a tribology test to determine an appropriate coating for the tribology system according to the present invention is shown. The time course of the coefficient of friction between the reference material A1 and the Al-CrO material D2 and the anti-antibody derived from the steel material is shown. The observed and measured wear of the material from FIG. 3 is shown. Figures 3 and 4 show wear of the anti-antibody in the SRV test with the exemplary layers. The time course of the friction coefficient of the illustrated materials A1 and D2 by the counter-antibody made of aluminum oxide is shown in FIGS. 3 to 5. The observed and measured wear of layers A1 and D2 with the counter-antibody according to FIG. 6 is shown. Shows anti-antibody wear after SRV test under dry conditions in contact with coatings A1 and D2. The time lapse of the A1 and D2 friction coefficients with the steel ball as the counter-antibody under the lubrication test condition with the first lubricant is shown. The wear of layers A1 and D2 after the SRV test under the lubrication condition shown in FIG. 9 is shown. 9 and 10 show the wear of the steel vs. antibody after the illustrated SRV test. The time lapse of the coefficient of friction of A1 and D2 with the aluminum oxide sphere as an anti-antibody under the lubrication test condition by the first lubricant is shown. The wear of layers A1 and D2 after the SRV test under the lubrication conditions according to FIGS. 11 and 12 is shown. The wear of the anti-antibody after the SRV test under the lubrication conditions shown in FIGS. 11 to 13 is shown. 15A-15C show the time of friction coefficient of materials A1, D1 and D2 for lubrication SRV test with aluminum oxide vs. antibody at room temperature (FIG. 15A), 100 degrees Celsius (FIG. 15B) and 160 degrees Celsius (FIG. 15C). Show the progress. The time course of the coefficient of friction of materials A1, D1 and D2 for the lubrication SRV test with aluminum oxide vs. antibody at 100 degrees Celsius is shown. The time course of the coefficient of friction of materials A1, D1 and D2 for the lubrication SRV test with aluminum oxide vs. antibody at 160 degrees Celsius is shown. A comparison of layer wear and anti-antibody wear of layer systems A1 and D2 for the lubrication SRV test illustrated in FIGS. 15A and 15C is shown.

A general description of the embodiment is first made, followed by a detailed description of the embodiment with reference to the drawings.

In one embodiment, the tribology system comprises a first body and a second body each forming a component of an internal combustion engine, specifically a piston, a piston ring or a cylinder, and the surfaces of the first and second bodies are in operation. Includes a first material area and a second material area that contact each other to form a tribological contact in at least some of the regions, the first material area and / or the second material area being a layer based on chromium oxide or aluminum oxide. Formed as, it has particularly favorable properties for critical tribology systems located near the combustion chamber of an internal combustion engine.

Layers based on chromium oxide or aluminum oxide can be applied in different processes to different materials, including compact materials typical for internal combustion engines.

Steel (eg quality 42CrMo4) is a typical material from which pistons are manufactured. Further typical materials for the piston and its running surface in the piston connector (and further the piston skirt) are for example a perite aluminum-silicon alloy with 11-13% Si and a small amount of additives of Cu, Mg and Ni. Is. For example, there are also light metal composites in which reinforcing elements made of ceramics, carbon fibers and porous metal materials are specially arranged in the piston region where particularly high stress is applied.

The cylinder is usually part of a crankcase and can be manufactured from, for example, cast iron alloys or aluminum-silicon alloys in monometal designs. The running surface of such a cylinder is formed directly on the material for casting.

In so-called coating techniques, the cylinder sleeve is inserted into the crankcase. In this case, the sleeve is made of GCI material, aluminum material, or even an aluminum-silicon alloy and is inserted, pressed, shrunk or cast into the crankcase in a properly machined receptacle.

In the so-called composite technique, a cylindrical body made of a composite of suitable metal and ceramic materials is inserted into a mold and infiltrated with a molten aluminum alloy under high pressure to form a crankcase.

The cylinder running surface of all cylinders is designed as a tribology running partner and provides a sealing surface for pistons and piston rings by fine bored or turning and subsequent honing.

There are various designs and materials for piston rings that act as metal seals to seal the combustion chamber to the crankcase. Steel or gray cast iron materials are widely used. In this case, it is also common practice to reinforce the ring running surface. The ring running surface forms a cylinder slide path, i.e. a wear resistant protective layer and a tribology system. In addition to the ring running surface coatings already mentioned, chrome ceramic layers, chrome diamond layers or molybdenum-based coatings are also provided. In a nitriding or nitrifying carburizing process, nitrogen and, in some cases, carbon can be incorporated onto the surface of the piston ring by diffusion.

There is a design in which the first material area and the second material area made as a coating are respectively arranged on the surface of the component forming the running surface. For components, ie pistons, piston rings or cylinders, these are the piston shaft sliding paths of the piston, the ring running surface of the piston ring, and the cylinder sliding paths inside the cylinder. Each of these surfaces forms a running surface that forms the tribology system according to the invention and can be designed as a layer based on chromium oxide or aluminum oxide.

First material area in the first body which is formed as a piston ring, a layer having a chemical composition (A l- xCr-y) 2O3 chemical composition based on aluminum oxide chromium having a (A l- xCr-y) 2O3 There is a design. Here, 0.1 <x <1 and y <0.5, 0.5 <x <1 and y <0.5, or x = 0.7 and y = 0.3. Such coatings exhibit positive tribological properties in both dry and lubricated conditions for different friction partners (second material areas on the cylinder running surface).

In another design, the second material area of the second body formed as a cylinder is a mixed alumina-chromium having a composition of 10% to 100% by weight Cr2O3 and a corresponding 90% to 0% by weight Al2O3. It is an oxide layer. Such a layer was applied to the cylinder running surface by a suitable coating method (eg using thermal spraying) and had the composition (All - xCr-y) 2O3 shown above (formed by the first material area). ) A good tribology partner for other layers based on aluminum oxide chromium.

There are designs that can further improve the tribological properties by positively affecting the surface roughness. Here, as the surface roughness Ra, the following values in μm units, that is, 1 ≦ Ra ≦ 0.5; 0.15 ≦ Ra ≦ 0.4; Ra = 0.15 or Ra = 0.4 are the first materials. The following values apply to the area, namely 0.1 ≤ Ra ≤ 0.5; 0.15 ≤ Ra ≤ 0.45; Ra = 0.15 or Ra = 0.45.

There are designs in which the material area is formed using thermal spraying. The sprayed material, which can be a powder mixture with different components such as Al2O3 and Cr2O3, is introduced into a concentrated high energy heat source, fused or partially melted and coated at high speed in the form of sprayed particles. It is charged on the surface of the target base material. This process is particularly suitable for coating wide surfaces such as cylinder running surfaces or even piston shaft slide paths. Common methods are high speed frame spraying (HVOF), so-called cold gas spraying, arc spraying, and plasma spraying. The composition of the resulting layer approximately corresponds to the composition of the starting material (powder mixture).

In thermal spraying, the layer thickness is 50 mm to 400 mm, more specifically 150 μm to 800 μm.

There are also designs in which one of the materials is formed using the PVD method (Physical Vapor Deposition), specifically cathodic spark evaporation. In a well-known PVD method, the deposition of ions, atoms or molecules from the gas phase or plasma creates a tribology protective layer on the surface of the substrate (the base material of the component to be coated). For this purpose, the required starting material (eg, metal, ceramics, etc.) is thermally evaporated or atomized and recondensed on the component.

Both so-called cathode spark evaporation and so-called cathode atomization (or MSIP (Magnetron Sputter Ion Plating)) are processes established long ago and are used for coating tools and components, which are often used. Different layers can be deposited.

For example, there are designs in which the material area formed by the PVD method has a layer thickness of 10 to 30 μm.

There are also designs in which one material area is formed as a layer based on Mo, MoN, MoCuN, DLC or ta-C and one material area is formed as a layer based on chromium oxide or aluminum oxide.

Mo, MoN, and MoCuN are resistant layers that improve tribological properties.

The DLC (diamond-like carbon) layer generally comprises a so-called thin film system consisting essentially of carbon and is applied using PVD or CVD (Chemical Vapor Deposition) methods. These layers are graphite, diamond-like, or amorphous carbon, or hydrocarbon layers similar to plasma polymer layers.

The ta-C based layer is also a so-called DLC layer, distinguished by a predetermined ratio between graphite and diamond-like bonds. Here, the diamond-like joint is dominant. Such a ta-C based layer also provides excellent tribological properties, specifically in a tribological combination with a chromium oxide or aluminum oxide based layer.

There are designs in which at least one of the layers has a universal hardness of at least 80 GPa. The hardness of the layer is often an indicator of wear resistance.

The present invention specifically relates to an internal combustion engine including the tribology system according to the present invention. The tribology system described above is particularly advantageous for components that are thermally stressed by the sliding friction load in the cylinder / piston area. These systems are similar to the tribology system formed from the piston shaft sliding path (piston skirt sliding path) and the cylinder sliding path, and are the tribology of the piston ring 8/9 (plural rings) and the cylinder sliding path. Including the system.

There are designs that provide the piston with at least one additional surface area formed as a layer based on chromium oxide or aluminum oxide. These areas specifically include the piston ring groove area, the piston crown, or even the piston shaft. Here, a heat-resistant and robust hard layer helps transfer the high stresses in these areas to the base material.

Returning to FIG. 1, this figure illustrates a component of an internal combustion engine 100 including a cylinder 101 in which pistons 102 that vibrate during operation are arranged in a schematic vertical sectional view. The piston 102 is provided with three piston rings 103 arranged in the piston ring groove 104. The cylinder wall 105 has a cooling channel 106, and the actual cylinder bore is formed here by an inserted (optional) cylinder liner 107. A cylinder running surface is formed on the inner surface 108 of the cylinder liner 107.

The piston 102 has a piston crown 109 at its upper end. The cylindrical piston ring groove area 110 has a boundary on the piston crown 109 and joins the piston connector 111.

On the one hand the cylinder 101 or cylinder sleeve 107 (if any) and on the other hand the piston ring 103 or piston connector 111 form the tribology systems 1 and 2.

FIG. 1A shows the tribology system 1. Here, the piston ring 103 forms the first body, and on the surface thereof, at least in the area of the ring running surface 112, the first material area 11 is, for example, a (All - 0.7Cr-0.3) 2O3 layer. It is formed as a layer based on aluminum oxide such as. Regarding other compositions according to the present invention, (All - xCr-y) 2O3 applies to the following. Here, 0.1 ≦ x ≦ 1 and y ≦ 0.5, and 0.5 ≦ x ≦ 1 and y ≦ 0.5. The layer thickness is 10 to 30 μm and the hardness is at least 18 GPa. The layer has a surface roughness (Ra in units of μm) of Ra = 0.15 or Ra = 0.4 and is in the range of 0.1 <Ra <0.5 in other embodiments. Other suitable coatings for piston ring 103 are shown in Table 1b as C2 and D2.

The second material area 12 is formed as a layer of the cylinder sliding path 108, the layer being formed from a mixture of alumina and chromium oxide, having an Al2O3 weight content of 62% by weight and a Cr2O3 weight content of 38. By weight%. The surface roughness is Ra = 0.45 μm (E1 in Table 1a). Alternatively, the first material area is formed as a chromium oxide (Cr2O3) layer with a surface roughness of Ra = 0.15 μm (D1 in Table 1a).

Alternatively, the second material area 12 is formed from a chromium oxide layer, constitutes a weight% content with a chromium oxide content of 10 to 100, and a corresponding complementary weight with an aluminum oxide content of 90 to 0. Make a%. Another suitable coating for the second material area can also be the layer system shown as A1, B1 and C1 in Table 1a.

As described above, the single or multiple piston rings 103 (first main body) and the cylinder 105 or cylinder sleeve 107 (second main body) have contact surfaces 112 and 108, respectively, and the single or multiple first material areas 11. And with the second material area 12, a tribology system is formed. Here, the contact surfaces slide against each other during operation.

That is, there is an operating condition in which a large dry friction exists at the top dead center and the bottom dead center of the piston where the piston speed is low or becomes zero. The lubricating film between the two surfaces formed by the engine oil is then severely destroyed.

Wet friction or lubrication friction occurs during the reciprocating movement of the piston between the reversal points. The engine oil then forms an effective lubricating film between the material areas 11 and 12. This greatly reduces friction and wear.

Mixing friction conditions may also arise in which the lubricant is not present as a complete film between the material areas 11 and 12 but is available in the recesses on the surface. This lubricating effect is stronger on high surface roughness (eg on a polished surface) than on a smooth surface due to low surface roughness (eg on a polished or matte surface) with low lubricant absorption capacity. Become.

The second tribology system 2 is shown in FIG. 1B. Detailed example 1B shows the piston connector 111 on the surface 113 on which the first material area 11 is formed. The surface is provided with the coatings shown in Table 1a as A1, B1, C1, D1 or E1. Alternatively, the surface 113 may also have the different coatings mentioned above in connection with the coating of the cylinder slide path 108. Again, as in the first tribology system 1, dry friction, lubricating friction or mixed friction occurs during operation depending on the state of movement of the piston 102 in the cylinder 105.

Other surface areas of the piston can also be provided with an additional optional coating, while the piston crown (see FIG. 1C) can also be provided with a layer 114 that improves heat resistance and pressure resistance. Another layer 115 may be provided to the piston ring groove area 110, more specifically to the area of the piston ring groove 104. Here, layers A1, B1, C1, D1, E1 listed in Table 1a, and further layers based on molybdenum, molybdenum nitrogen, molybdenum copper nitrogen, DLC or ta-C can also be used.

Further, for example, when the piston ring 103 is provided with a layer based on chromium oxide or chromium oxide (in the first material area 11), the layer (second material area 12) that cooperates with the layer is provided with Mo, MoN, MoCuN, and the like. It also applies that it can be formed in the cylinder sliding path 108 as a layer based on DLC or ta-C.

On the contrary, when such a layer is provided to one or more piston rings 103, the cylinder slide path 108 is detailed with a layer based on chromium oxide or aluminum oxide, specifically above or below. A layer having such properties is provided. The same applies to the tribology system formed by the cylinder sliding path 111 and the piston shaft sliding path 113.

In the following, FIGS. 2-16 are used to illustrate the test, among other things, along with related test settings and some test results that lead to the aforementioned embodiments of the present invention. An important test of this type is the Vibration Friction Wear (SRV) Test (DIN 51834), which can characterize material wear and friction behavior. These tests can simulate many tribological situations of subsequent application, allowing useful preselection of body coating and anti-antibody. That is, in a real combustion engine, only fine-tuning is required, as a solution that is optimized to some extent in advance can be used when choosing a coating. This is achieved by adjusting the parameters of the SRV test, such as contact pressure or temperature, in a manner that reflects the results of the engine tests already performed.

Such SRV tests were used for the purposes of the study according to the invention and the test parameters were selected in a manner that simulated incomplete lubrication at tribological contacts. The parameters were used both in the case of incomplete lubrication and in the case of "drying" or testing without lubricant. Experiments have shown that such tests provide information on two basic wear behaviors. The drying test investigates all the seizure behaviors of the tribological contact partners described above and reveals the relative wear of the tribological partners. Lubrication tests under such high contact pressures simulate inadequate lubrication. These test conditions provide information about tribopartner wear as well as a coefficient of friction that allows relative comparison of material combinations.

Various layer materials were investigated in the experiment. The layer selection was made to further develop and improve the tribological contact between the piston ring of the internal combustion engine and the cylinder slide path. That is, the layers were formed using the thermal spraying method in the first group 1 and the PVD method in the second group 2, preferably by sputtering, more preferably by reactive cathode spark evaporation.

Two coating methods were used to coat the specimen. That is, the sample sample of Group 1 was given a layer that was experimentally shown to be suitable for application to the cylinder slide path, or a layer that could be examined for this application.

Group 2 samples were coated with materials that have been experimentally shown to be suitable for piston ring coatings, or materials that should be characterized for such coatings. The layers were deposited on planar specimens and partially post-treated. The test was performed with both steel counter-antibody (100Cr6) and aluminum oxide.

FIG. 2 shows a schematic configuration of the device used to perform the SRV test and describes the terms used in the text. Testing has been performed on a fairly large number of layered materials, but not all of them are listed here.

Two important technical goals for the development of the internal combustion engine field are to reduce wear to extend component service life and service time intervals, and to reduce friction loss to improve efficiency.

An important aspect also concerns the temperature stability of the materials used in internal combustion engines. The trend here is to improve the temperature stability so that the engine efficiency can also be increased by the combustion process occurring at high temperatures. Searching for temperature-stable layer materials that protect the compact material surface at these high temperatures and have good tribological properties at both ambient and high temperatures is another important reason for these investigations.

FIG. 2 describes the principle of SRV test under drying conditions (left side) and lubrication conditions (right side). A tribology system or tribo system consists of two tribo partners, namely body (K) and counter-antibody (GK). In the experiment, spherical polished GK made from steel (100Cr6) and aluminum oxide was used while K was coated with a layer. K is firmly clamped to the base and heated. The load L is applied simultaneously while the GK moves on the K in a vibrating manner by horizontal vibration due to the forces indicated by the two arrows on the coated surface of the K. In the lubrication test (right side), the lubricant S is added to this vibration.

Description of the experiment

Tables 1a and b show the layer materials tested. Some of these materials have already been technically introduced or are already eligible for engine testing (A1, B1, C1). In addition, additional materials with unknown tribological properties but with improved temperature stability (D1, E1, C2, D2) were tested. These materials are mainly derived from oxides, some of which belong to the content of the present invention. Tables 1a and b list only some of the materials tested and also show the surface roughness that these layers had. This, of course, depends on different post-processing.

Since these studies used only common methods such as honing, grinding or matting for these post-treatments, the technical implementation of the present invention is not only for coatings but also for post-treatments. Is also guaranteed. The table groups the layer materials according to the coating method. That is, a layer intended to be applied to the cylinder running surface is provided in Table 1a, and a layer intended to be coated on the piston ring is provided in Table 1b. This division was made because it is appropriate that different coating methods have different degrees for ring and liner coatings, but should not be considered a limitation.

Moreover, it is not essential that layer materials of the same chemical composition produced in different coating methods also have the same properties in a tribology system. This can be due, for example, to different layer thicknesses, or mechanical properties with respect to layer porosity or residual stress. Thermal spraying was used on the layers of the cylinder running surface to produce coatings with a thickness of 150 μm to 800 μm. The PVD method was used for coating the piston ring material. The PVD method is reactive cathode spark evaporation for the layer selected in this case. However, other coating methods such as thermal evaporation or sputtering can also be used for this purpose.

A flat sample was coated. All the samples produced by thermal spraying were post-treated to have a surface roughness corresponding to the standard honing used during production for the purpose of post-treatment of the thermal sprayed cylinder slides.

Layers produced using spark evaporation were post-treated with no post-treatment or using standard matting methods. Allocation, selection, and further details of the layer material to the manufacturing process are given in Tables 1a and 1b, along with the type of post-treatment and the surface roughness obtained.

Polished steel (100Cr6) and aluminum oxide spheres were used as counter-antibodies in the SRV test. Both drying and lubrication tests were performed with two different oils. The tests were conducted at ambient temperature and at temperatures up to 160 ° C., close to the stability limits of the lubricants used, to also investigate the stability of the layer at elevated temperatures.

The following results were obtained by the test.
1. 1. Curve of coefficient of friction as a function of time 2. Coating wear under various conditions 3. Anti-antibody wear under various conditions

The results are given in tabular form. For the coefficient of friction, the values obtained at the end of each test are included in the table. Evaluation of coating and anti-antibody wear is based on optical evaluation of light microscopy wear images and quantitative evaluation of optical scanning surface profiles. An example is given for all types of results and the conditions examined in the SRV test for the purpose of a good understanding of the values given in tabular form.

FIG. 3 shows the time course of the coefficient of friction of the post-treated low alloy steel layer (A1) and the polished Al—Cr—O layer (D2) using the polished steel balls as counter-antibodies. The SRV test was performed dry, i.e. without lubrication. It can be seen that the coefficient of friction at the end of the measurement time is 0.86 for A1 and 0.76 for D2. The noise of the curve D2 is higher in the oxide layer than in the low ferroalloy.

Under these test conditions, tribology systems have a coefficient of friction value that will be shown to those skilled in the art as "seizure" in tribology contact. Such values should be avoided for the applications described herein.

FIG. 4 shows layer wear. For this purpose, an optical microscope image of the layer surface was obtained after the test (image in the upper column). A clear change in the layer surface is seen in the area about 1 mm long in which the vibrating steel ball moves. EDX measurements can be used to detect anti-antibody (100Cr6) material for both A1 and D2. That is, the material moves from the counter-antibody to the layer (burn-in) and exhibits anti-antibody wear.

The surface was mechanically scanned perpendicular to the direction of oscillating motion to characterize layer wear in detail. This is indicated by a white line in the drawing. A confocal white light microscope of type "μ-Surf"® from the manufacturer Nanofocus was used as the device for this measurement. The surface profile of A1 obtained by scanning shows an increase in surface roughness due to partial material application and partial layer wear of A1. Less wear is observed in the surface profile of D2. It is applied to both edges of the vibrating movement, with almost no ablation in the middle, except for scratches. Based on the wear scale (1 is no wear, 5 is strong wear), this wear is rated as about 2 for A1 and 1-2 for D2.

The size of the coefficient of friction can be explained to those skilled in the art of tribology. Values around 0.8 are typical for the dry friction of steel on steel, which is achieved by moving the material into layers. Further wear values are given in Table 2. In the values of B1 and C2, a minus sign was added after the wear value. This is believed to indicate that very strong material movement of the anti-antibody occurred in these two layers, i.e., there was no wear but the anti-antibody material accumulated in the layers. The values in the table indicate that the layer is highly wear resistant to steel, with the exception of C1. However, in tribology systems, it is shown that when a steel wear resistant layer is combined with steel as an anti-antibody, it is necessary to avoid drying conditions for the described layer. Under these conditions, even with improved surface roughness, the anti-antibody material cannot be clearly prevented from seizure.

In addition to the wear of the coated body, the wear of the anti-antibody is of course important in optimizing the wear behavior of the tribology system in the tribology system. Therefore, in FIG. 5, the wear of the anti-antibody, in this case polished 100Cr6 steel sphere, is examined by acquiring an optical microscope image of the sphere area in contact with the layer. The diameter of the so-called wear cap is a measure of wear, from which the wear volume can still be calculated. A scale of 1 to 5 is used again here for the purpose of evaluating the table. Again, 1 means no wear and 5 means very high wear. With respect to the photograph in FIG. 5, A1 is evaluated as 4 and D2 is evaluated as 3.

Even more noticeable is the low noise over time in the coefficient of friction of D2. Examining layer wear using light microscopy images and surface profiles in the wear area gives different results for the two layers (FIG. 7). Obvious layer wear was observed in relation to A1 and estimated to be 4. Surprisingly enough, no layer wear can be found in D2. There is only one type of smoothness in the contact area. Based on this, layer wear is evaluated as 1.

Aluminum oxide vs. antibody wear is shown in FIG. The wear on the anti-antibody is clearly less for both layer systems than on the 100Cr6 anti-antibody case. For A1 (upper left), the anti-antibody shows a contact surface with many scratches. Subsequent measurements of the roundness of the anti-antibody (bottom left) confirm that the surface of the aluminum oxide anti-antibody is rough. Otherwise, no significant change in sphere radius would be observed. It can be assumed that this material pair causes fractures leading to such rough surfaces. The background to these outbreaks has not yet been clarified. There is no observed anti-antibody wear for D2 (right column). This is a surprising result for unlubricated tribology systems operating under high contact pressures. The circular areas in the modified surface quality photographs for A1 and D2 are tested under selected conditions and are characterized only by deformation of the region of the body and anti-antibody contact areas typical for each material pair. The deformation area of the case is shown. Therefore, this deformation does not necessarily result in the wear cap that was present in the case of 100Cr6 spheres. Again, this evidence is provided by a surface scan by nanofocus, which initially gives a radius and indicates flattening of the sphere. Significant results for the dry SRV test are provided by the body and anti-antibody available layer pairs of layers based on chromium oxide and aluminum oxide.

The results of the SRV test with lubricant are presented below. Tests were conducted with various lubricants leading to different coefficients of friction. However, in terms of wear, these differences are small or indistinguishable. Usually, different coloring of the contact area is visible. Examination has shown that this is primarily due to the different additives in the oil. Since the treatment of additives is not the subject of the present invention, these differences will not be addressed in detail.

FIG. 9 shows the coefficient of friction over time for A1 (1) and D2 (2). This was measured with diesel oil as a lubricant (referred to here as oil 1) and steel balls as an anti-antibody. A1 has a coefficient of friction of 0.20 in the break-in operation, while D2 has a coefficient of friction of 0.18. The relative difference in the coefficient of friction compared to the drying test was smaller. That is, the effect of the material under lubrication conditions became less noticeable. The surface quality of the coating also has a significant effect. That is, the surface pores or porous structures that appear in A1 as a result of the thermal spraying process are suitable for retaining the lubricant on the surface, thus making the tribology system safe, especially in the case of inadequate lubrication. In summary, this can also be seen by comparing C2 and D2. This is because the unpolished layer C2 has a lower coefficient of friction than the polished one. Table 3 shows all the coefficients of friction for the lubrication SRV test, along with steel as a counter-antibody.

The layer wear obtained under these test conditions is shown in FIG. A1 shows a low layer wear of a value of 2, and otherwise shows a smoothing effect in the contact area. Layer wear is not measured for D2 (value 1). Again, although not clearly demonstrated in the measured surface profile, smoothing can occur. Other values for layer wear are again given in Table 3. Only low wear is measured for layers A1, B1 and C1, while all layers based on chromium oxide and aluminum oxide show no wear.

The wear of the steel vs. antibody due to the lubricant oil 1 is shown in FIG. Surface discoloration is seen for both configurations. In the case of A1, the surface profile of the 100Cr6 sphere shows slight wear (values 1-2). That is, the surface discoloration is caused by the elastic deformation of the contact surface alone, and the discoloration is caused by the thin film mainly generated from the additive in the oil or its decomposition product. For D2, the size of the discoloration of the contact surface is similar to that of A1, but the surface profile of the 100Cr6 sphere shows low wear with a value of 2. The steel body is subject to even more significant wear due to layers E1 and C2. All layers based on chromium oxide and aluminum oxide have very high microhardness above 20 GPa (measured according to ISO 14577 standard) and the surface accordingly when these layers are used with steel as counter-antibody. Choosing quality is important.

The results of the SRV test with aluminum oxide vs. antibody are of great interest. This is because under the drying conditions of the two tribo partners against D2, there can be no wear that has already been determined. Again, FIG. 10 shows the passage of friction coefficient over time. At the end of the test, the result was a value of 0.19 for A1 and 0.18 for D2. Again, the relative effect of the coating material on the coefficient of friction is lower than in the drying test. Obviously, the formation of surfaces that result from the interaction of material surfaces, oils and additives and that themselves exhibit discoloration plays an important role. B1 has the highest coefficient of friction. Otherwise, a coefficient of friction of 0.18 was measured for all other materials. In these tests, the coefficient of friction is surprisingly lower than that of the A1 and C1 layers already introduced for steel.

FIG. 13 shows layer wear. This is very low relative to A1 (value 2), but rather shows only a smoothing effect. This is particularly good behavior for backgrounds where the layer contains many holes. This in turn indicates that these surface geometries contribute to good tribological properties, that is, the lubricant is retained in the recesses of the layer to reduce friction loss. Layer wear cannot be measured for D2 (value 1). The layer is stable. However, the effect of smoothing is suspected here as well. It is B1 (value 5) and further C1 (value 4) that show high wear. Specifically, layer B1 shows how important it is to coordinate the body and anti-antibody. This is because B1 has the lowest coefficient of friction for steel and the highest coefficient of friction for aluminum oxide.

FIG. 14 characterizes the wear of aluminum oxide vs. antibody. Neither A1 nor D2 show wear of the sphere (both have a value of 1). The roughness of the surface area measured in the surface profile is characteristic for a given porosity of the material. Scratches are caused by a small ejection of material between the layer surface and the anti-antibody during the test, which, in contrast to the actual engine test, can be transferred away with the oil during our test setup. Absent.

Tables 2 and 3 summarize the results of the layer materials tested for the two counter-antibody materials against different test conditions. Quantitative estimates were obtained from the measurements exemplified in the above sentence. Based on these surveys, the results of the SRV tests so far are summarized as follows.

SRV: Drying with 100Cr6 as anti-antibody-There is considerable wear of 100Cr6 steel anti-antibody for all tests.
-The test is stable at a coefficient of friction in the range around 0.8. This is a lubricating material pair antibodies for each layer (moved) due to the fact that eventually results in a steel-steel contact. Therefore, a clear and high wear of the anti-antibody is observed for all layers examined here.

SRV: Drying with Aluminum Oxide as Anti-Anti-Anti-Aluminum Layers A1, B1 and C1 show layer wear, which is more than other common materials not included in the table for the layer selected here. Is also low.
-The oxide layers investigated are divided into two groups. The group with high surface roughness (E1) has a coefficient of friction around 0.8 and shows strong noise over time of the coefficient of friction. The second group (D1, C2, D2) has a coefficient of friction around 0.6, which in turn stands out from the other layers. The layers in this group have a surface roughness of Ra less than 0.4 μm.
-Apart from the smoothing effect, all oxide layers (D1, C2, D2) based on Cr and Al—Cr show no layer wear.

SRV: The coefficient of friction of all layers lubricated and examined with 100Cr6 as a counter-antibody showed a value of less than 0.2, with B1 and D1 being the lowest.
-Chromium oxide and non-chromium aluminum oxide layers (A1, B1, C1) show a low wear value of 2.
-Layer wear cannot be detected in the layers (D1, C2, D2) based on chromium oxide and chromium aluminum oxide.
All other layer materials have a small anti-antibody wear value of 1-2 or 2, with the exception of E1 and C2, the hard oxide layers with large surface roughness. The surface roughness of the layer under lubrication conditions and with 100Cr6 as an anti-antibody clearly plays an important role, and if such a material pair is realized, the break-in behavior needs to be optimized, and the layer roughness Ra Should be less than 0.2 μm.

SRV: The coefficient of lubrication / friction with aluminum oxide as an antibody is in the range of 0.18 to 0.20 except for B1 (0.21).
-Layer wear is very high for B1, moderate for C1 and E1, and low for A1. In the case of layers D1, C2 and D2 based on chromium oxide and chromium oxide, layer wear can be observed.
-Tests produce slight wear on the anti-antibody for most layers, but no wear on A1, D1 and D2.

Ultimately, the test is also performed at high temperatures. For this purpose, a different, somewhat temperature-stable oil 2 was used. The use of this oil did not, in principle, change anything from previous SRV test findings at room temperature. Oil 2 gave a slightly different coefficient of friction, but gave no other quantitative results for the wear behavior of the coating and anti-antibody.

This does not mean that this also applies to all other oils. The use of other additives alone can result in dramatic changes in the coefficient of friction. However, this is not the content of these studies and will not be explained in detail. The oil 2 used for the SRV test at high temperature was stable for testing up to a temperature of 160 ° C.

Table 4 shows the test layers tested at room temperature (RT), 100 ° C and 160 ° C. The table shows only a few selections of test layers and focuses primarily on the layering materials that are the subject of the present invention.

Again, as already mentioned above, the time course of the coefficient of friction, layer wear, and anti-antibody wear were tested against these layers and anti-antibody. In the following, this procedure will be demonstrated again using an example, but this time there is no light microscopy image and only the surface profile is shown. The coefficient of friction was determined and the layer wear and anti-antibody wear were quantitatively evaluated in the same manner as described above.

15a-15c show the time course of the coefficient of friction for the lubrication (oil 2) SRV test on coating systems A1, D1 and D2 with aluminum oxide as counter-antibodies. Comparison of different coating materials at room temperature reveals clear differences between A1 and D1 and D2. These decrease at high temperatures, but do not disappear. For all temperatures, layers D1 and D2 have the lowest coefficient of friction.

FIG. 16 compares layer wear against layers A1 and D2 with anti-antibody wear. A1 has a low layer wear of value 2, while D2 shows no layer wear. In addition, there is no aluminum oxide vs. antibody wear on both layers.

In summary, the following can be said for the SRV test at high temperature.

SRV: Lubrication at high temperature with 100Cr6 as a counter-antibody-The coefficient of friction for all investigated layers shows a value around 0.2. At room temperature, layers D1 and D2 have values of about 0.18 and 0.16, respectively. This is significantly lower than that of A1 (0.20). At high temperatures, these differences gradually disappear, but layers based on chromium oxide and aluminum oxide still have the lowest coefficient of friction.
-A1 shows low layer wear over the entire temperature range, while oxide layers D1 and D2 show no layer wear. On the other hand, many non-oxide layers are subject to wear. With the exception of B1 and C2, there is only slight wear on the anti-antibody. Here, the surface roughness of the layer, and perhaps the break-in behavior of the tribo system, also plays an important role. After a predetermined time cycle, anti-antibody wear stabilizes over the size of the contact surface.

SRV: Lubrication at high temperature by aluminum oxide as an anti-antibody ・ The coefficient of friction at room temperature is slightly low and shows a slight increase with respect to high temperature. However, in all cases around 0.2, the layers D1 and D2 based on chromium oxide and chromium oxide are lower than in the case of A1.
-Low layer wear occurs at all temperatures for A1 and large wear occurs for B1. Layers based on chromium oxide and aluminum oxide have no wear.
-There is no measurable anti-antibody wear on all layers.

Tribology systems 1 or 2 having bodies 105, 107 and counter-antibodies 103, 111 that together form a tribology contact have been described. The surface 108 of the bodies 105, 107 is coated with the first coating 12 at least in the contact area, and the surface 112 of the anti-antibodies 103, 111 is coated with the second coating 11 at least in the contact area. At least one of the first and second coatings 12 and 11 is a layer based on chromium oxide or chromium aluminum oxide.

In the tribology system 1 or 2, the other layers 11 and 12 may include layers based on Mo, MoN, MoCuN, DLC or ta-C.

In the tribology system 1 or 2, both the first and second coatings 12, 11 may include a layer based on chromium oxide or chromium oxide.

At least one of the coatings 12 and 11, preferably both of the coatings 12 and 11, may have a chemical composition of (All-xCr-y) 2O3. Here, 0.1 ≦ x ≦ 1 and y ≦ 0.

At least one of these coatings 12, 11, preferably both coatings 12, 11 can have a hardness of 18 GPa or higher.

The tribology system can be part of an internal combustion engine 100 that is preferably designed for gasoline, diesel or gas combustion.

For example, the main body can be a piston ring 103, and the counter-antibody can be, for example, a cylinder running surface 108. Preferably, the other surface of the internal combustion engine 100 is coated with a layer based on chromium oxide or aluminum oxide, especially the cylinder ring groove 104, the piston skirt (piston connector 111), the piston connector sliding path 113, and / or the piston. Crown 109 is preferred.

Claims (12)

Tribology system (1; 2)
The; (107 101); each Gapi piston (102), the piston ring (103) or the cylinder first body forming a component of an internal combustion engine (100) comprising (101, 107) (102 105) and the second body Including
The surfaces (112, 108, 113) of the first body (102; 103 ) and the second body (101; 107) come into contact with each other in at least some regions during operation to form a tribological contact. It has a first material area and a second material area (11, 12).
One of said first material area及beauty before Symbol second material area (11, 12) is formed as a layer based on chromium oxide,
A tribology system (1; 2) in which the other of the first material area and the second material area (11, 12) is formed as a layer based on aluminum oxide chromium. Each of the first material area and the second material area (11, 12) is, component (101 and 107, 103, 102) forming the running surface is an array on the surface of, tribology of claim 1 System (1; 2). The first material area (11) in the first body formed as the piston ring (103) is a layer based on aluminum oxide chromium having a chemical composition of (All-xCr-y) 2O3.
Here, claim 1 or claim 1, wherein 0.1 ≦ x ≦ 1 and y ≦ 0.5 , 0.5 ≦ x ≦ 1 and y ≦ 0.5, or x = 0.7 and y = 0.3. 2. The tribology system (1; 2) according to 2. The second material area (12) in the second main body formed as a cylinder (101, 107) contains 10% by weight to 100% by weight of Cr2O3 and correspondingly 90% by weight to 0% by weight of Al2O3. The tribology system (1; 2) according to any one of claims 1, 2 or 3, which is a layer having the tribology. The first material area (11) has a surface roughness Ra in μm to which 0.1 ≦ Ra ≦ 0.5, 0.15 ≦ Ra ≦ 0.4 , Ra = 0.15 or Ra = 0.4 applies. Have,
From claim 1, the second material area has a surface roughness to which 0.1 ≦ Ra ≦ 0.5, 0.15 ≦ Ra ≦ 0.45 , Ra = 0.15 or Ra = 0.45. The tribology system (1; 2) according to any one of 4. One of said first material area and the second material area (11, 12) is formed by a thermal spraying method, tribological system according to any one of claims 1 to 5 (1: 2). The tribology system (1; 2) according to claim 6, wherein the material areas (11, 12) formed by the thermal spraying method have a layer thickness of 150 μm to 800 μm. Wherein the first material area and one of the second material area (11, 12), is more formed on a PVD method including a cathode spark evaporation, tribological system according to any one of claims 1 7 (1 2). The tribology system (1; 2) according to claim 8, wherein the material area formed by the PVD method has a layer thickness of 10 μm to 30 μm. The tribology system (1; 2) according to any one of claims 1 to 9 , wherein at least one of the layers has a hardness of at least 18 GPa. An internal combustion engine (100) having the tribology system (1; 2) according to any one of claims 1 to 10. At least the piston (102) is in and / or piston crown (109) in the piston ring groove area (104, 110) in the piston shaft (111), formed as a layer based on chromium oxide or aluminum oxide chromium The internal combustion engine (100) according to claim 11 , which has one additional surface area.

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